1. Field of the Invention
This invention relates, generally, to salinity measurements in near shore or estuarine environments. More particularly, it relates to means and methods for protecting toroidal conductivity sensors from biological growth thereon that causes a slow decrease in conductivity readings.
2. Description of the Prior Art
Non-toroidal salinity sensors are particularly susceptible to the deleterious effects of biological growth on the sensors, due in part to the exposed electrodes found in such sensors. The application of anti-foulant chemicals does little to stem the problem, especially in the biologically active lower latitudes.
Toroidal salinity sensors are more resistant to such fouling, but organisms nonetheless grow slowly upon them and eventually cause them to produce erroneous readings. Significantly, the fouling occurs so slowly that the decrease in conductivity falls too gradually to be noticed until the readings are clearly bad. Thus, many months may pass where a sensor is fouled and generating inaccurate readings without the knowledge of those collecting data from it.
What is needed, then, is a salinity sensor that is not subject to fouling by biologically active organisms.
However, in view of the prior art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the pertinent art how the identified need could be fulfilled.
The long-standing but heretofore unfulfilled need for a method and apparatus that protect a toroidal conductivity sensor from fouling is now met by a new, useful, and nonobvious invention. The steps of the method include enclosing the sensor in a hollow enclosure and providing at least one opening in the hollow enclosure to enable water to flow into the hollow enclosure so that the sensor is immersed therein. Biologically active marine organisms are filtered from the water as it flows through the at least one opening to inhibit growth of marine organisms on the sensor. Accordingly, the sensor does not lose its sensitivity due to marine organisms growing thereon.
The structure of the novel apparatus that protects a submerged sensor head from fouling by biologically active marine organisms includes an enclosure having a hollow interior for housing the sensor head. At least one opening is formed in the enclosure to admit water into the hollow interior. A filter is disposed in the at least one opening for removing marine organisms from water admitted into the hollow enclosure. Accordingly, the sensor head is submerged in water that is substantially free of marine organisms.
More particularly, the enclosure includes a tubular base made of a straight pipe, an end cap having a tubular part that ensleeves a first end of the tubular base, and a closure means formed integrally with the tubular part. A first plurality of openings is formed in a preselected part of the end cap and a first plurality of filter means is positioned within each opening of the first plurality of openings.
A coupler has a tubular part that ensleeves a second end of the straight pipe and further includes a diameter-reducing part formed integrally with the tubular part of the coupler. The diameter-reducing part has a frusto-conical configuration. A second plurality of openings is formed in a preselected part of the coupler and a second plurality of filter means is positioned within each opening of the second plurality of openings.
An annular neck extends from the diameter-reducing part. A sensor means includes an elongate base and a sensor head is mounted to a first end of the elongate base. The annular neck is adapted to receive the elongate base therethrough so that the sensor head is positioned within the hollow enclosure.
A clamping means maintains the elongate base against sliding displacement relative to the annular neck so that the sensor head has a fixed position within the hollow enclosure. The clamping means includes a pipe that is split axially to accommodate the elongate base of the sensor means. The elongate base is slideably received within the axially split pipe, and the clamping means further including an annular band adapted to be positioned in overlying relation to the axially split pipe and tightened.
An important object of this invention is to protect a submerged toroidal conductivity sensor from fouling by marine organisms.
A more specific object is to immerse the sensor in a housing to protect it from marine organisms while ensuring that sea water within the hollow interior of the housing has the same conductivity as sea water external to the housing so that the sensor makes true measurements.
Another object is to filter biologically active marine organisms from the sea water that is within the hollow interior of the enclosure.
Another object is to position a toroidal conductivity sensor in sufficient spaced apart relation to metallic or other electrically conductive materials so that such materials do not interfere with measurements made by the sensor.
These and other important objects, advantages, and features of the invention will become clear as this description proceeds.
The invention accordingly comprises the features of construction, combination of elements, and arrangement of parts that will be exemplified in the description set forth hereinafter and the scope of the invention will be indicated in the claims.